All verses are quoted from the NASB anything in [square brackets] is added by me for clarity.

Einstein in his Special Theory claimed that time is relative to the observer. This non-intuitive claim seems to have been verified by experimentation (comparison of atomic clocks in different orbits).

If a Christian has a problem with the notion of time being relative then they should read Psalm 90 -

"For a thousand years in Your [God's] sight Are like yesterday when it passes by, Or as a watch in the night." Psalm 90:4

Now since this is in the Psalms it is obviously speaking poetically. But just because it is poetry does not make it meaningless. It seems to be saying that God experiences time differently to us. In fact the Apostle Peter seems to have understood it this way. Peter writing against people who don't believe Jesus is coming again writes -

"Know this first of all, that in the last days mockers will come with their mocking, following after their own lusts, and saying, `Where is the promise of His [Jesus' 2nd] coming? For ever since the fathers fell asleep, all continues just as it was from the beginning of creation.' " 2 Peter 3:3-4

He argues against this by quoting the ideas contained within Psalm 90 -

"But do not let this one fact escape your notice, beloved, that with the Lord one day is like a thousand years, and a thousand years like one day." 2 Peter 3:8

Again, clearly stating that God experiences time differently to us. In other words at least at this level time is relative, according to the Scriptures. So the Christian should not have a problem with the notion of the relativity of time.